Flexible thermoelectric composite materials with self-healing ability for harvesting low-grade thermal energy

Directly converting waste heat from environment or human body into electricity without any moving parts is crucial in low-grade waste heat harvesting and wearable electronic applications. In this work, a sunlight self-healing thermoelectric generator that harvests energy from the human body is reported. Self-healing polyurethane gives the thermoelectric generators self-healing capacity, and the p/n-type thermoelectric component is composed of an organic-inorganic composite including carbon nanotubes and semiconductor nanoparticles. The ternary thermoelectric composite film exhibits a largely improved thermoelectric performance compared to the single component due to the energy-level configuration and interfacial energy filtering effect, and the power factor of self-healing p-type composite film is up to 355.6 ± 4.8 μW/(m·K2). Moreover, the healing efficiencies of the thermoelectric performance are both higher than 85% for the self-healing p-type and n-type composite films. The film-shaped thermoelectric generator, which is made up of 5 pairs of p/n-type counterparts, finally produces a voltage of 19.1 mV and power of 0.6 μW at a temperature difference of 60 K. Furthermore, a fibrous thermoelectric generator is also created and it produces a 2.1 mV open-circuit voltage and 1.39 nW power at a temperature difference between a human palm and the ambient environment.